A variety of procedures and systems are used to transport liquids in bulk quantities. For instance, vehicles designed specifically for liquid transport are available in motor, sea, and rail transport forms. Because vehicles designed exclusively for liquid cargo cannot usually be used for other types of cargo, the ability to effectively employ these vehicles is often limited. In a preferred situation, a liquid cargo vehicle may be used to transport a first type of liquid cargo to a first destination and then may be used to “backhaul” a second type of liquid cargo from the first destination to the point of origin. While such a preferred situation optimizes the utility of the liquid cargo container, many logistical considerations must be overcome to be practical on a large scale. Thus, for the most part, the productivity of many conventional liquid transport vehicles is reduced.
Rather than being limited to using specifically designed liquid transport vehicles, others have attempted to use general purpose vehicles for transport of liquid cargo. One known method is to secure a deformable liner to inner walls of a cargo vehicle. The bottom of the liner rests on the floor of the vehicle. As the vehicle is loaded, the liquid presses the liner against the floor and walls, thus filling the vehicle.
While useful for some types of cargo, this method is undesirable for food or other products that may be susceptible to contamination or spoiling. Additionally, since the cargo is unrestrained in the liner-general purpose vehicle, any movement of the vehicle may cause a surging weight shift that can destabilize the vehicle. Baffles have been used to reduce the surging problem in this type of container, but the baffles increase the cost of the liner. Baffles also increase transport surface area exposed to the cargo, which increases the possibility of contamination. Moreover, baffles ultimately have a relatively limited effect on surging due to the high mass of most liquid cargos.
Flexitank or pillow containers have been developed that are sealed to prevent exposure to ambient air. These flexitank containers typically have air pockets that allow surging when the vehicle is in motion. However, bulkheads are often required to hold the ends of the bags in place when vehicle doors are opened. These bulkheads are typically expensive and time consuming to install. In addition, approval from government agencies (such as the U.S. Food and Drug Administration) often is required to use flexitanks. Moreover, when transporting food stuffs or other consumable items, flexitanks often require inner liners, which add to their cost.
As shown in FIG. 11, when attempting to convert and utilize a conventional transport system 701 to carry a liquid cargo, a dry box shipping container 703 usually must be lined with plastic or cardboard 705 prior to the installation of the flexitank 707 in order to prevent punctures and leakage of the flexitank 707. If the flexitank 707 is punctured, or if a seal breaks, an entire cargo can be lost due to drainage.
As is evident from FIG. 11, the flexitank 707 when fully filled can place extreme stresses on the walls of the dry box shipping container 703, which can cause the walls and doors to bow out during transport. This is extremely prevalent during rail voyages where rail cars are shunted. Total losses of such dry box shipping containers are not uncommon, with claims and damages ultimately being incurred by the shippers and costs passed on to consumers.
In addition to the foregoing problems, due to ensuing and expensive environmental clean-up issues, many steamship lines simply have banned the use of the flexitank or pillow containers.
Shipment of bulk liquids has also been attempted by loading the liquid into drums and securing the drums inside the transport vehicles. While this approach tends to reduce exposure to air, thereby reducing risk of contamination to some cargo, this method has proven to be unsuitable for most food items, since avoiding all metal contact with food items is practically impossible and contamination from other sources is nevertheless possible.
Yet a further disadvantage of using drums for liquid cargo shipment is the high costs entailed. The drums themselves are expensive, and filling, loading, and unloading each drum are expensive, labor-consuming activities. Additionally, as the drums are loaded onto the vehicle, they must be restrained, or else movement of the vehicle may cause the drums to be damaged or overturned in transit. Thus, the cost of using drums is increased further due to the need to provide pallets on which to secure the drums during transit. More specifically, the cost of the pallets and fumigation become part of the cost of the cargo. Also, the space taken by the pallets during the trip reduces the amount of usable cargo space. Finally, the drums themselves must be disposed of or returned at the end of each transit.
Another attempt to ship bulk liquid, viscous, or powder cargo has been to use containers approved by the International Organization for Standardization (ISO). Unfortunately, these stainless steel ISO containers are very expensive and, to be commercially viable, must be used for hundreds of shipments and must be amortized over decades. Additionally, substantial costs are invariably incurred for repositioning and repairing ISO containers. All told, the high costs associated with ISO containers ultimately add to the cost of the cargo being transported.
While addressing the basic desirability of using general purpose transport vehicles to move bulk cargo, such as liquid, previous efforts have failed to provide a single bulk transport system, which is inexpensive to manufacture and which is durable enough to be cleaned and reused. A solution must also be robust enough to prevent leakages and not put undue stress on dry box shipping container walls and doors. Moreover, a bulk cargo transport system is also needed in the shipping industry that can pay for itself in three to four shipments and that can be amortized over about three to six months as opposed to, e.g., 20 years.